Playlist question (for auto updating a playlist)

[DDPS]

This functionality actually already exists (and has for a long, long time) in the form of Bookmarks.

What is the essential difference between a Bookmark and a Smart Playlist?

Two differences are that they are visible in ARC and they can be browsed as playlists (put into folders, tagged, etc). While bookmarks are accessed from one long list drop down menu. I was hoping smart playlist would introduce more complex operators (AND OR Nested Operators). I understand they are not? G

The main thing is that they are not available in ARC.